The present invention relates to a safety diagnosis system for a structure for diagnosing safety of a structure by directly measuring a displacement of the structure.
Conventionally, when safety of a structure is diagnosed, acceleration sensors are installed at two points or more including at least a foundation part and an upper floor of the structure, for example, and the safety of the structure is diagnosed based on an acceleration data measured by the acceleration sensor. When an earthquake occurs, an acceleration record is obtained from the acceleration sensor and an absolute displacement is obtained by second-order integration of the acceleration record. A vibration mode form of a building assumed from the absolute displacement is applied, an absolute acceleration and a relative displacement of each floor of the building are calculated, and a performance curve of the building is obtained by taking the absolute acceleration as an axis of ordinate and the relative displacement as an axis of abscissa. Further, a requirement curve of the building is theoretically acquired based on an input seismic motion as observed, and a residual aseismic performance of the building is determined from a comparison between the performance curve and the requirement curve. Or a maximum value of values obtained by dividing a difference of the absolute displacement between continuous upper and lower floors by a floor height, that is, a maximum inter-layer deformation angle of each floor is calculated. From the calculated maximum inter-layer deformation angle of the structure, the safety of the structure or a necessity of restoration of the structure is diagnosed.
However, in a case where an acceleration sensor is used, since a displacement amount of the structure cannot be directly collected as measurement data, it is necessary to obtain the displacement amount by applying the second-order integration to an acceleration data as acquired. Therefore, the displacement amount of the structure needs to be acquired by calculation and consequently there is a problem that errors are accumulated and an accuracy is deteriorated. Further, as a purpose of avoiding a drift, a case where a high-pass filter passage processing is used at the same time is general. Therefore, measurements requiring a long time such as measurement of a difference between a position before an earthquake and a position after the earthquake of the structure, for example, and an evaluation of an aftereffect variation and a residual deformation of the structure gradually developing after the occurrence of the earthquake based on the measurement are impossible in principle.
Japanese Patent Laid-Open Publication No. 2000-214267 relates to an earthquake observation system, where a plurality of seismometers installed on arbitrary floors aboveground and underground are connected to a personal computer via a LAN. When a vibration occurs in a building due to an earthquake or the like, it is configured such that the vibration is detected by each seismometer and held in a server in each seismometer and the detection of vibration is transmitted from the server to the personal computer. A configuration in which, an earthquake observation record held in the server of each seismometer can be inspected by operating the personal computer and accessing each seismometer, is disclosed.
Further, Japanese Patent No. 3952851 discloses a technique of evaluating a residual aseismic performance of a building from a comparison between a performance curve and a requirement curve of the building.
Further, “Vibration response estimating method of building structure using only one acceleration sensor”, Architectural Institute of Japan Technical Reports, Vol. 19, No. 42, pp. 461 to 464, June 2013 relates to a vibration response estimating method of a building structure using only one acceleration sensor, where one acceleration sensor is installed on the top floor of a building, and absolute accelerations of all floors of the building is acquired based on an acceleration from the acceleration sensor. A configuration in which an absolute displacement is calculated by integrating an absolute acceleration, and a maximum inter-layer deformation angle per each floor is estimated from the absolute displacement as calculated, is disclosed.